登录后访问设置请问

package filters;import java.io.IOException;import javax.servlet.Filter;import javax.servlet.FilterChain;import javax.servlet.FilterConfig;import javax.servlet.ServletException;import javax.servlet.ServletRequest;import javax.servlet.ServletResponse;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import javax.servlet.http.HttpSession;public class LoginFilter implements Filter{    public void init(FilterConfig conf) throws ServletException{                }    }        public void doFilter(ServletRequest req,ServletResponse res,    FilterChain chain) throws ServletException,IOException{        HttpServletRequest hReq = (HttpServletRequest)req;        HttpServletResponse   hres=(HttpServletResponse)res;         HttpSession s = hReq.getSession(true);        Object ac = (Object) s.getAttribute("account");                if(ac==null){            ((HttpServletResponse)res).sendRedirect("/user/loginForm");            ／／是在这里加吗？改如何写请教下        }        chain.doFilter(req,res);                        }    public void destroy(){      // TODO Auto-generated method stub    }      }